Dry cleaning systems are known. Additionally, dry cleaning systems that use vapor and liquid carbon dioxide are known. The system employs a washing vessel, in which articles to be washed may be placed. Vapor and liquid carbon dioxide is transferred to the washing vessel. The carbon dioxide is pressurized inside the washing vessel. Pressures inside the vessel may be equal to approximately 700-900 psi. Liquid and vapor carbon dioxide is capable of cleaning the articles. Additives, such as organic solvents, may be supplemented. After washing, the washing vessel is depressurized. Liquid and vapor carbon dioxide are removed from the washing vessel. The clothes may be removed from the washing vessel, after which a new washing cycle may be initiated.
A drawback of the known systems and methods is loss of vapor carbon dioxide. Blow off of vapor carbon dioxide for depressurizing the washing vessel leads to losses of material. Additionally, in other parts of the systems, i.e. in piping systems and connections thereof, losses of carbon dioxide may occur. The loss of this carbon dioxide needs to be replenished in a new washing cycle.
Additionally, the losses of liquid and vapor carbon dioxide are associated with a relatively low thermodynamic efficiency.